Method and means for the excitation of x-ray tubes



June 5, 1934. M o so 1,961,702

METHOD AND MEANS FOR THE EXCITATION OF X-RAY TUBES Filed April 27, 1931ATTORNEY Patented June 5, 1934 UNITED S PATENT oFF-ics poration ofDelaware Application April 27, 1931, serial No. 533,079

' 3 Claims.

companies varies in different sections of the country. The presenttrend, however, of these companies is to standardize on'60 cycle currentand throughout my specification and claims I will refer to 60 cycles asstandard frequency. This variation in frequency presents ever perplexingproblems to manufacturers of electrical apparatus and thisisparticularly true in the X-ray art. 'As'an example of one of theseprob- Iems, the thermionic cathodesof X#ray and rectifier tubes, whenconstructedfor operation on say cycle current will not operatesuccessfully on '60 cycle current, due to the cooling of' these heavierfilaments during operation of the tube. The converse condition islikewise exceedingly unsuccessful due to overheating of the cathodes andthe shortening of the life of the tube.

It is, thereforaan object of'my invention to provide an X-ray system inwhich a thermionic discharge device is utilized wherein electricalenergy of one frequency may be impressed upon'the electrodes of thedevice and electrical energy of a different frequency may be utilized toheat the cathode of the device.

Another object of'my invention is the provisionof an X-ray system inwhich electrical energy of one frequency may be utilized to energize theelectrodes'of an X-ray or rectifier tube and electrical energy ofanother frequency may be utilized for heating the cathodes thereof.

"Another objectof my inventionis the provision of an X-ray system inwhich electrical energy of one frequency may be utilized to energize theelectrodes of an X-ray and rectifier tube and electrical energy of thesame or a different frequency may beutilized'for heatingthecathodes'thereof as desired. I

A further object of my invention is the provision of an X-ray circuit inwhich an X-ray tube designed for operation on currents of one frequencymay be successfully utilized with a thermionic rectifier tube designedfor operation on currents of a different frequency.

Still further objects of my invention will become apparent to thoseskilled in the art by reference to the accompanying drawing wherein theby'the motor. A pair of conductors 16 and 17 extend'from'this standardfrequencey generator 14 'tothepri'mary winding 18 of a low tensiontr-anssingle figure is a diagrammatical representation of an X-ray circuitembodying the details of construction and arrangement of the variousparts in accordance with my invention.

Referring now to the drawing in detail I hat/e6 shown a generator 5 forgenerating electrical energy of the usual commercial alternating currentpotential of 25 cycles per second and I shall refer to this as a lowfrequency or less than standard frequency source. A pair of supplyconductors 6 and 7 extend from this generator and'are connected to theprimary winding 8 of a high-tension transformer 9.

A hand operated switch 10 is provided in the conductor 7 for opening andclosing the circuit from the source 5 to the primary winding 8. The

conductors 6 and 7 also extend to'a small syn- 'electricalenergy'such asa battery 13.

A small alternating current generator 14 of commercial potential and ofstandard 60 cycle frequency is coupled to the synchronous motor 12 bymeans of a shaft 15 and is thus driven former 19 for the purpose ofenergizing the latter. A pair of conductors 2i) and 22 are connected tothe low frequency conductors 6 and '7 and extend to two terminals 23 and24 of a double-pole double-throw switch 25.

Another pair of conductors 26 and 27 are connected to the conductors 16and 1'7 from the standard frequency source 14' and extend to two contactterminals 28 and 29 of the switch 25. The primary winding 30 of alow'tension transformer 32 is connected by means of a pair of conductors33 and 34 to the center of blades 35 and 36 of the switch 25. In thismanner, when the switch is in a position in which the blades 35 and 36are in'contactwith the terminals 23 and 24, the primary winding 30 isconnected to the low-frequency source 5, and when the blades 35 and 36 vare in contact with the terminals 28 and 29 the primary winding 30 isconnected to the standard frequencysource 14.

A thermionic rectifier tube 37, is arranged to have its cathode heatedfrom the secondary wind- I ing 38, of the low-tension transformer 19through conductors 39 and 40, and an X-ray tube 42, likewise receivesheating currents for its cathode from a secondary winding 43 by means ofconductors 44 and 45 which extend from the low tension transformer 32. Aconductor 46 extends from the anode of the X-ray tube 42 to one end ofthe secondary winding 47 of high-tension transformer 9 and the other endof the secondary winding 47 is connected by means of a conductor 48 tothe conductor 39 leading to the rectifier tube 3'7. The anode of therectifier tube 3'7 is connected by means of a conductor 49 to theconductor 44 leading to the cathode of the X-ray tube 42.

The X-ray tube 42 may be a tube designed for operation on currents ofless than standard frequency or on standard frequency currents. Thsrectifier tube 37 is designed to have its cathode heated by currentsfrom a standard frequency source and currents of less than standardfrequency may be impressed across the electrodes of the rectifier tube.In this manner discharge tubes of standard manufacture may be utilizedon commercial alternating current lines wherein the frequency is lessthan standard or 60 cycle.

The operation of my device is as follows: the synchronous motor 12 isconnected to the lowfrequency source and is excited from the directcurrent source 13. This motor in turn drives the standard frequencygenerator 14 through the shaft 15. The switch 10 is closed allowing theprimary winding 8 of high tension transformer 9 to become energized andthe primary winding 18 of the low tension transformer 19 is energizedfrom the generator 14.

The double pole switch 25 is then closed establishing contact betweenthe blades 35 and 36, and the contact terminals 23 and 24 whichenergizes the primary winding 30 from the lowfrequency source 5 by meansof the conductors 20 and 22. Energization of the primary windings 18 and30 of low tension transformers 19 and 32 respectively, energizes thesecondary windings 38 and 43 of these transformers and thus heats thecathodes of the rectifier tube 37 and X-ray tube 42.

The closing of the switch 10 and the resulting energization oftransformer 9 causes high-potential energy to fiow from the secondarywinding 47 by means of conductor 48, rectifier tube 3'7, conductor 49,X-ray tube 42, and thence over conductor 46 back to the secondarywinding 47. This circuit is completed and high-potential currents willflow during each half-wave of the alternating current cycle in themanner just described and during the remaining half-wave current will beprevented from flowing by means of the valve action of the rectifiedtube 37.

Should it be desired to energize the cathode of the X-ray tube 42 from astandard frequency source instead of from the source of less thanstandard frequency the switch 25 is merely changed into contact with theterminals 28 and 29. This enables standard frequency currents to fiowfrom the source 14 by means of conductors 16, 1'7 and 26, 2'7 andenergize the primary winding 30 of low-tension transformer 32 which inturn heats the cathode of X-ray tube 42 with standard frequencycurrents.

It can thus be readily seen by those skilled in the art that I haveprovided an X-ray system in which thermionic discharge tubes may bereadily utilized in which currents of less than standard frequency maybe impressed upon the electrodes of the tubes and currents of standardfrequency be utilized to heat the cathodes of these tubes. This systempermits the employment of tubes of standard frequencies which arereadily adaptable uniformly to all sections of the country regardless ofvariation in frequencies in different sections.

What is claimed is:

1. In an X-ray system, an X-ray tube provided with a cathode to beheated, a high-tension transformer for supplying energy to said X-raytube, a low-tension transformer for supplying heating current to thecathode of said X-ray tube, a source of electrical energy of a givenfrequency common to the primary windings of both said transformers forenergizing the same, a thermionic discharge device provided with acathode to be heated and connected in a circuit with said Y-ray tube andsaid high tension-transformer, means connected to said source ofelectrical energy for generating electrical energy of a frequencydifferent from that of said first mentioned source, and a lowtensiontransformer connected to said means for supplying heating current to thecathode of said discharge device.

2. In an X-ray system, an X-ray tube provided with a cathode to beheated, a high-tension transformer for supplying energy to said X-raytube, a low-tension transformer for supplying heating current to thecathode of said X-ray tube, a source of electrical energy of less thanstandard frequency common to the primary windings of both of saidtransformers for energizing the same, a thermionic discharge deviceprovided with a cathode to be heated and connected in a circuit withsaid X-ray tube and said high-tension transformer, means connected tosaid source of electrical energy for generating electrical energy of astandard frequency, a low-tension transformer connected to said sourceof standard frequency for supplying heating current to the cathode ofsaid discharge device, and means for disconnecting said first mentionedlow-tension transformer from said source of less than standard frequencyand connecting the same to said source of standard frequency if desired.

3. In an X-ray system, an X-ray tube provided with a cathode to beheated, a high-tension transformer for supplying energy to said X-raytube, a low-tension transformer for supplying heating current to thecathode of said X-ray tube, a source of electrical energy of less thanstandard frequency common to the primary windings of both saidtransformers for energizing the same, a thermionic discharge deviceprovided with a cathode to be heated and connected in a circuit withsaid X-ray tube and said high-tension transformer, a synchronous motorconnected to said source of less than standard frequency, a standardfrequency generator coupled to said synchronous motor, and a low-tensiontransformer connected to said standard frequency generator for supplyingheating current to the cathode of said thermionic discharge device.

MONTFORD MORRISON.

